Study of electroactive biofilms from wetlands of French Guiana : application to microbial fuel cells

Les biofilms électroactifs (EA) sont des consortia bactériens mono ou pluri-espèces, qui ont la faculté d’échanger des électrons provenant de leur métabolisme avec les surfaces solides conductrices des électrodes. Cette découverte est à l’origine d’un nouveau dispositif énergétique : la pile à combustible microbienne (PACM). Depuis les années 2000, la littérature scientifique sur les biofilms EA et sur les PACM explose, notamment grâce à la découverte de bactéries capables de transférer par voie directe – par des pili ou protéines transmembranaires – des électrons vers les électrodes. Plusieurs sources de bactéries EA ont été à ce jour découvertes, allant de cultures pures à des communautés bactériennes plus complexes. Ces dernières sont issues de milieux aqueux naturels (milieux marins ou d’eau douce), industriels ou urbains (effluents d’industrie, eaux usées domestiques). La plupart de ces sources bactériennes proviennent d’environnements de climat tempéré. Dans ce travail de thèse, plusieurs sols de milieux humides de la Guyane ont été identifiés comme étant de sources de bactéries EA. Les expériences menées sous potentiel d’électrode imposé et constant ont permis d’étudier l’adhésion à la surface d’électrode des biofilms EA issus de la flore endogène des milieux sélectionnés. La formation de bioanodes et de biocathodes a été possible en présence respectivement d’acétate et d’oxygène dans les milieux. Une étude par voltammétrie cyclique a mis en évidence les pics d’oxydo-réduction en lien avec les échanges électroniques du biofilm EA et de l’électrode. En optimisant la procédure de formation des biofilms EA par chronoampérométrie (surface d’électrode plus importante, apport en continu et progressif du substrat), une densité de courant maximale de 12 A/m2 et un rendement faradique de 24 % ont été obtenus. Une autre méthode pour former des biofilms EA à partir d’un milieu choisi, la mangrove, a consisté à utiliser deux prototypes de PACM : une pile à compartiment unique et à cathode à air, et une pile benthique. Dans les deux cas, les biofilms EA ont pu être formés et étudiés, complétant certaines observations faites sous potentiel imposé. La PACM benthique s’est avérée être la plus proche d’une application à grande échelle puisqu’elle a été complètement autonome : anode et cathode utilisant uniquement le milieu pour fonctionner. Elle a pu être étudiée en laboratoire comme sur le terrain.Electroactive biofilms (EA) are mono or multi-species bacterial consortia, which have the ability to exchange electrons from their metabolism with solid surfaces of conductive electrodes. This discovery is the basis for a device of energy production: microbial fuel cell (MFC). Since the 2000s, the scientific literature on EA biofilms and MFC explodes, thanks to the discovery of bacteria that are able to transfer directly – by pili or trans-membrane proteins – electrons to electrodes. Several sources of EA bacteria were discovered to date, ranging from pure cultures to more complex bacterial communities. Those last are from natural (marine and freshwater), industrial or urban (industrial effluents, domestic wastewater) aqueous environments. However, the vast majority of these are from temperate environments.In this thesis, several wetland soils of French Guiana have been identified as sources of EA bacteria. Experiments under poised and constant electrode potential were used to examine adherence to the electrode surface of EA biofilms from the endogenous flora of selected environments. Formation of bioanodes and biocathodes was possible in the presence respectively of acetate and oxygen in the media. A study by cyclic voltammetry showed the redox peaks related to electronic exchanges between EA biofilm and electrode. By optimizing the process of EA biofilm formation by chronoamperometry (larger electrode surface, providing continuous and progressive substrate), a maximum current density of 12 A/m2 and a coulombic efficiency of 24% were obtained.Another method to form EA biofilms from a chosen medium (mangrove) was to use two MFC prototypes: a single compartment and air cathode one, and a benthic one. In both cases, the EA biofilms have been trained and studied supplementing certain observations made under poised polarization. MFC benthic proved to be the closest to a wide application since it was completely autonomous, anode and cathode only using the medium to function. It has been studied in the laboratory and in the field

MIC of carbon steel in Amazonian environment: Electrochemical, biological and surface analyses

International audienc

Tropical mangrove sediments as a natural inoculum for efficient electroactive biofilms

International audienc

Electrochemical and microbial monitoring of multi-generational electroactive biofilms formed from mangrove sediment

International audienc

Etude des biofilms électroactifs issus des milieux humides de la Guyane Française (application aux piles à combustible microbiennes)

Les biofilms électroactifs (EA) sont des consortia bactériens mono ou pluri-espèces, qui ont la faculté d échanger des électrons provenant de leur métabolisme avec les surfaces solides conductrices des électrodes. Cette découverte est à l origine d un nouveau dispositif énergétique : la pile à combustible microbienne (PACM). Depuis les années 2000, la littérature scientifique sur les biofilms EA et sur les PACM explose, notamment grâce à la découverte de bactéries capables de transférer par voie directe par des pili ou protéines transmembranaires des électrons vers les électrodes. Plusieurs sources de bactéries EA ont été à ce jour découvertes, allant de cultures pures à des communautés bactériennes plus complexes. Ces dernières sont issues de milieux aqueux naturels (milieux marins ou d eau douce), industriels ou urbains (effluents d industrie, eaux usées domestiques). La plupart de ces sources bactériennes proviennent d environnements de climat tempéré. Dans ce travail de thèse, plusieurs sols de milieux humides de la Guyane ont été identifiés comme étant de sources de bactéries EA. Les expériences menées sous potentiel d électrode imposé et constant ont permis d étudier l adhésion à la surface d électrode des biofilms EA issus de la flore endogène des milieux sélectionnés. La formation de bioanodes et de biocathodes a été possible en présence respectivement d acétate et d oxygène dans les milieux. Une étude par voltammétrie cyclique a mis en évidence les pics d oxydo-réduction en lien avec les échanges électroniques du biofilm EA et de l électrode. En optimisant la procédure de formation des biofilms EA par chronoampérométrie (surface d électrode plus importante, apport en continu et progressif du substrat), une densité de courant maximale de 12 A/m2 et un rendement faradique de 24 % ont été obtenus. Une autre méthode pour former des biofilms EA à partir d un milieu choisi, la mangrove, a consisté à utiliser deux prototypes de PACM : une pile à compartiment unique et à cathode à air, et une pile benthique. Dans les deux cas, les biofilms EA ont pu être formés et étudiés, complétant certaines observations faites sous potentiel imposé. La PACM benthique s est avérée être la plus proche d une application à grande échelle puisqu elle a été complètement autonome : anode et cathode utilisant uniquement le milieu pour fonctionner. Elle a pu être étudiée en laboratoire comme sur le terrain.Electroactive biofilms (EA) are mono or multi-species bacterial consortia, which have the ability to exchange electrons from their metabolism with solid surfaces of conductive electrodes. This discovery is the basis for a device of energy production: microbial fuel cell (MFC). Since the 2000s, the scientific literature on EA biofilms and MFC explodes, thanks to the discovery of bacteria that are able to transfer directly by pili or trans-membrane proteins electrons to electrodes. Several sources of EA bacteria were discovered to date, ranging from pure cultures to more complex bacterial communities. Those last are from natural (marine and freshwater), industrial or urban (industrial effluents, domestic wastewater) aqueous environments. However, the vast majority of these are from temperate environments.In this thesis, several wetland soils of French Guiana have been identified as sources of EA bacteria. Experiments under poised and constant electrode potential were used to examine adherence to the electrode surface of EA biofilms from the endogenous flora of selected environments. Formation of bioanodes and biocathodes was possible in the presence respectively of acetate and oxygen in the media. A study by cyclic voltammetry showed the redox peaks related to electronic exchanges between EA biofilm and electrode. By optimizing the process of EA biofilm formation by chronoamperometry (larger electrode surface, providing continuous and progressive substrate), a maximum current density of 12 A/m2 and a coulombic efficiency of 24% were obtained.Another method to form EA biofilms from a chosen medium (mangrove) was to use two MFC prototypes: a single compartment and air cathode one, and a benthic one. In both cases, the EA biofilms have been trained and studied supplementing certain observations made under poised polarization. MFC benthic proved to be the closest to a wide application since it was completely autonomous, anode and cathode only using the medium to function. It has been studied in the laboratory and in the field.CAYENNE-BU (973022101) / SudocSudocFranceF

Energy harvest with mangrove benthic microbial fuel cells

International audienceBenthic microbial fuel cells (BMFCs) are continuous electricity generators using electroactive microorganisms and organic matter from aquatic environment, respectively, as catalysts and substrate. In this paper, first a low-cost PVC-made structure is constructed to harvest electricity from mangrove environment located in French Guiana. An in situ BMFC has given power density of 30 mW/m2 of the anodic surface area. This performance has been confirmed by experience in laboratory where inter-electrode distance and electrode surface area appeared to be power increasing factors. However, the output power of one BMFC is not used to supply real devices such as autonomous sensors. Second, to meet this expectation, in parallel and in series associations were considered. These associations were made in order to increase the output voltage and consequently the power, to reach levels that can supply small sensors (about 3 V). Finally, to improve the performance of the series association and to avoid the voltage reversal phenomenon, a voltage balancing circuit was simulated and added to the series connections. With balancing method, the cell voltage of BMFCs can be equalized, and the performances can be improved. This allows an optimal energy harvesting and a better global efficiency of the set

Electrochemical and microbial monitoring of multi-generational electroactive biofilms formed from mangrove sediment

International audienc

Corrosion inhibition of C38 steel by alkaloids extract of Geissospermum laeve in 1M hydrochloric acid: Electrochemical and phytochemical studies

International audienc

Bagassa guianensis ethanol extract used as sustainable eco-friendly inhibitor for zinc corrosion in 3% NaCl: Electrochemical and XPS studies

International audienceIn view of the huge advantages of green corrosion inhibitors and in order to solve the problem of environmental pollution in the process of cleaning the zinc metal, this study is the evaluation of Bagassa guianensis extract on the corrosion behaviour of zinc in chloride medium (3%) was realised using electrochemical techniques (polarisation and AC impedance). This study demonstrated that the plant extract of Bagassa guianensis is a real as sustainable and green inhibitor for zinc corrosion in 3% NaCl with an inhibition efficiency of about 97% at 100 ppm. The electrochemical reactions were both impacted by the existence of the green inhibitor on the basis of the polarization curves and a change towards the positive potentials was measured in the presence of the extract in 3% NaCl. A CPEα, Q determined by fit and graphical methods plotted by synthetic data, was utilized. In order to determine the chemical compounds mainly responsible for the corrosion inhibition of the extract, electrochemical studies were carried out on each family contained in the plant extract. To comprehend the adsorption mechanism of total extract and flavonoids extract for zinc in the saline solution, XPS technique was accomplished. The obtained results indicated the establishment of protective film inclosing the Bagassa guianensis extract and the flavonoids compounds. The mechanism of corrosion protection of Bagassa guianensis extract was discussed with PDP, EIS, isothermal adsorption model and XPS technique

Influence of sargassum on marine corrosion of carbon and stainless steels immersed in seawater on French West Indies Coast

International audienceSince 2011, the washed-up Sargassum are a concern for Caribbean region. These golden tides cause some environmental damages, and results significant negative impacts on health and economical costs. In this work, we studied the behaviour of carbon steel and stainless steel immerged on three sites more or less impacted by the presence of sargassum algae on the coasts of Martinique (French Antilles). Another experiment makes, at laboratory and on site (more and less impacted sites), to determine the influence of microorganisms with three conditions (sterile, non-sterile, non-sterile with sargassum). The comparative study of the corrosion of steels was carried out through structural (SEM, confocal microscopy) and electrochemical characterizations (EVT, PEIS and LPR) and bacterial community analysis. Significant differences of corrosion rates and surface morphologies were observed for the three studied sites. The more advanced surfaces degradation of metals observed at 7 days for carbon steel DC01 (2,2 ± 0,24 mm/year) and at 60 days for stainless steel 304L (0,5 ± 0,67 mm/year). For laboratory experiment, at 15 days, we observed similar trends with an increase of potentials for all conditions and sites for DC01 (0 days: -750 ± 15 mV; 15 days: -711 ± 6,38 mV) and for stainless steel 316L (0 days: -50 ± 10 mV; 15 days: 70 ± 30 mV). However, we have significant variations between samples at laboratory and at site. To more aggressive site there is an increase of potential for DC01 and a decrease of potential for 316L (-260 ± 63 mV). That is can be correlated with the establishment of biofilm for 316L (Unsal and al.,2016). An attempt was made to link its results with certain chemical parameters characteristic of the water at the sites studied and the quantity and state of decomposition of the Sargassum algae present